Spatially-resolved optical studies on intermixing of InGaAs quantum-dot laser structures by using an AlAs native oxide and thermal annealing

Abstract

We have studied the optical properties of InGaAs quantum dot (QD) laser structures with Al oxide (AlOx) as a current-blocking layer by means of photoluminescence (PL) and spatially-resolved micro-PL techniques. A dominant, broad PL emission due to the intermixing effect of the AlOx layer was observed at a PL emission energy higher than that of the non-intermixed region. To characterize the optical properties of the intermixed and the non-intermixed regions of InGaAs QDs, we performed low-temperature (77 K) micro-PL experiments. We observed InGaAs QD emission at about 1.1 eV in the Don-oxide AlAs region while the PL emission energy for the AlOx layer region was shifted to about 1.16 eV. For the reference sample without heat. treatment, only a PL emission at about 1.1 eV was observed. We conclude that the intermixing effect of the InGaAs QD region under an AlOx, layer is stronger than that of the InGaAs QD region under a non-oxided AlAs layer.